Precision control arrangement



Oct. 1968 HITOSHI ISHIMA 3,404,489

PRECI S ION CONTROL ARRANGEMENT Filed May 5, 1966 INVENTOR HITOSHIISHIMA United States Patent M 3,404,489 PRECISION CONTROL ARRANGEMENTHitoshi Ishima, Cook County, Ill., assignor, by mesne assignments, tothe United States of America as represented by the Secretary of the ArmyFiled May 5, 1966, Ser. No. 548,367 6 Claims. (CI. 51-58) ABSTRACT OFTHE DISCLOSURE A lens polishing machine that has a polishing element onan axially movable shaft secured to a pressure controlled diaphragmpiston of a frictionless forward cylinder. A double-acting piston of arearward cylinder has its connecting rod secured to the forward cylinderto control the position of the polishing element over a major distance,while the precision controlled diaphragm piston controls smallincremental positions and insures exertion of a predetermined pressureby the polishing element upon the work pieces. A ball bushing iseccentrically carried by the shaft and slidingly receives a guide pinsecured to the forward cylinder.

This invention relates to pneumatic cylinders, and more particularly, toa pneumatic cylinder employed as a feed control means in a lenspolishing machine.

One of the objects of the invention is to provide a polishing tool feedcontrol in which a predetermined pressure may be precisely exerted uponwork pieces being polished.

Another object of the invention is to provide such an arrangement havinga minimum of friction loss.

A further object is to provide the tool with a support having a minimumof bending moment under operating conditions.

In one aspect of the invention the control arrangement includes anaxially movable polishing tool shaft having piston means thereon whichincludes a flexible diaphragm connected between the shaft and itssupporting cylinder. The supporting cylinder has connected to its rearportion a piston rod of a double acting cylinder, as well as a fluidpassage communicatively connected just rearward of the diaphragm andhaving therein means for precisely controlling the pressure of fluidacting upon the piston means.

These and other objects, features and advantages will become apparentfrom the following description and accompanying drawings in which:

FIG. 1 is an elevational view partially broken away in section of apolishing tool arrangement embodying the principles of the invention.

FIG. 2 is a sectional view of the FIG. 1 arrangement with certainportions removed for clarity.

The support or yoke 11 (FIG. 1) of the lens polishing machine has spacedand aligned apertured legs 12 for appropriate drive connections to ameans (not shown) for imparting a desired translatory motion to theyoke. The hub of the yoke support 11 is centrally formed to have mountedtherein a pneumatic cylinder 13 of the control feed arrangement showngenerally at 14. The rear portion of the axially movable shaft 15 isencompassed within cylinder 13 and the lower or forward portion of theshaft 15 is suitably formed with means for connecting or attaching apolishing element 16 (dotted lines) which contacts one or more lensblanks or work pieces (not shown) that are mounted in a predeterminedmanner upon a rotary work-holder.

A rearmost double-acting pneumatic cylinder 18 has longitudinallymovable piston 19 operable between the two fluid control conduits 20,21. The connecting rod 22 of piston 19 is threadedly secured to acentral tapped recess 23 (FIG. 2) in the rear portion of cylinder 13.

3,404,489 Patented Oct. 8, 1968 Longitudinally spaced ball bushings 25,26 (FIG. 2) are retained by appropriate rings 27, 28 in end chambers 29,30 of three successive internal chambers within cylinder 13. The middlechamber 31 is separated from chamber 29 by an inwardly extending flange32 which provides a' forward stop for the skirt 33 of a pistonarrangement 34 secured to shaft 15 and axially operable within cham ber31. Piston means 34 includes a flexible rolling diaphragm 35 which hasits outer portions 36 appropriately secured in the sidewall of cylinder13. Shaft 15 is slidably mounted in ball bushings 25, 26 and has anoffset or eccentrically mounted ball bushing 38 secured in its rearportion for slidingly accommodating a guide pin 39 that is suitablysecured to the interior rear wall of cylinder 13. Shaft 15 isaccordingly recessed at 40 for receiving the forward portion of pin 39when the piston means 34 is in a partially or fully retracted position.

Fluid passage means 41 is appropriately secured to a cylinder wallopening 42 for communicatively connecting with chamber 31 rearwardly ofpiston means 34. Conduit 41 is suitably valved at 43, the gauge 44controlling the admission of fluid into the cylinder 13 behind therolling diaphragm piston arrangement.

Thus, the aligned pneumatic cylinders are constructed in a manner thatpiston 19 of rear cylinder 18 feeds or controls the position of thepolishing element 16 over a major distance and the pressure controlleddiaphragm piston 34 of the frictionless forward cylinder 13 controlssuch position over small increments and insures exertion of apredetermined constant contact pressure by the polishing element uponthe work pieces. This arrangement also permits use of a relatively shortforward cylinder shaft 15 having a substantially reduced bending momentunder operative conditions. The use of linear type ball hearings or ballbushings 25, 26, 38 as well as the rollowing diaphragm piston 34minimize the presence of friction in cylinder 13.

Various modifications, changes or alterations may be resorted to withoutdeparting from the scope of the invention as defined in the appendedclaims.

I claim:

1. A feed control for a polishing tool or the like to maintain precisionpressure by said tool against work pieces being polished, comprising anaxially movable shaft having means for attaching a polishing elementthereto,

a first cylinder encompassing a rear portion of said shaft,

a ball bushing eccentrically carried by said shaft rear portion,

piston means on said shaft and having a flexible diaphragm securedthereto, said diaphragm also being secured to a wall of said firstcylinder,

fluid passage means communicatively connected to said first cylinderrearward of said diaphragm,

a second cylinder having an internal double-acting piston for movementintermediate longitudinally spaced fluid control means, said pistonhaving a connecting rod secured to a rear portion of said firstcylinder,

a guide pin secured to said first cylinder rear portion and slidinglyreceived by said eccentric ball bushing, and

means in said passage for precisely controlling the pressure of fluidacting upon said piston means,

so constructed and arranged that operation of said second cylinderpiston will control the position of the polishing element over a majordistance, and the precision controlled piston means controls suchposition over small increments and insures exertion of a predeterminedpressure by the polishing element upon work pieces.

2. The structure of clai length substantially less than that of saidpiston rod.

3. The arrangement of claim 1 in which said diaphragm is a rollingdiaphragm and ball bushing means are disposed in said first cylinder forslidable engagement with said shaft.

In a polishing machine having a polishing element secured to an axiallymovable shaft for maintaining precision pressure against work piecesbeing polished,

first cylinder encompassing a rear portion of said 10 shaft, ballbushing eccentrically carried by said shaft rear portion,

piston means on said shaft and having flexible diaphragm securedthereto, said diaphragm also being secured to a wall of said firstcylinder,

fluid passage means communicatively connected to said m 1 wherein saidshaft has a means in said passage means for precisely controlling thepressure of fluid acting upon said piston means, so constructed andarranged that operation of said second cylinder piston will control theposition of the polishing element over a major distance, and theprecision controlled piston means controls such position over smallincrements and insures exertion of a predetermined pressure by thepolishing element upon work pieces.

5. The structure of claim 4 wherein said shaft has a lengthsubstantially less than that of said piston rod.

6. The arrangement of claim 4 in which said diaphragm is a rollingdiaphragm and ball bushing means are disposed in said first cylinder forslidable engagement with 15 said shaft.

References Cited UNITED STATES PATENTS Wine 5l165 Obecny 26931 XPressman 26933 Hastings 92-61 X 25 HAROLD D. WHITEHEAD, PrimaryExaminer.

